Novak Djokovic says he regrets the failure to win either the US or French Opens, despite playing some of the best tennis of his life in 2020.
Having won an eighth Australian Open in January, Djokovic was disqualified at the US Open after inadvertently hitting a line judge in the neck during his fourth-round clash with Pablo Carreno Busta.
He was then blown away by world No 2 Rafael Nadal in the final of the re-arranged French Open in October.
Djokovic remains on 17 Grand Slam titles while Nadal and Federer are on 20 each after the Spaniard clinched a record-extending 13th Roland Garros title.